diff --git a/src/gl/scene/gl_wall.h b/src/gl/scene/gl_wall.h
index 37501c6078..a317ac267b 100644
--- a/src/gl/scene/gl_wall.h
+++ b/src/gl/scene/gl_wall.h
@@ -99,6 +99,7 @@ public:
 		GLWF_GLOW=8,		// illuminated by glowing flats
 		GLWF_NOSPLITUPPER=16,
 		GLWF_NOSPLITLOWER=32,
+		GLWF_NOSPLIT=64,
 	};
 
 	enum
diff --git a/src/gl/scene/gl_walls.cpp b/src/gl/scene/gl_walls.cpp
index cd179a2653..ab6d710d4f 100644
--- a/src/gl/scene/gl_walls.cpp
+++ b/src/gl/scene/gl_walls.cpp
@@ -984,6 +984,7 @@ void GLWall::DoMidTexture(seg_t * seg, bool drawfogboundary,
 		//
 		FloatRect *splitrect;
 		int v = gltexture->GetAreas(&splitrect);
+		if (seg->frontsector == seg->backsector) flags |= GLWF_NOSPLIT;	// we don't need to do vertex splits if a line has both sides in the same sector
 		if (v>0 && !drawfogboundary && !(seg->linedef->flags&ML_WRAP_MIDTEX))
 		{
 			// split the poly!
diff --git a/src/gl/scene/gl_walls_draw.cpp b/src/gl/scene/gl_walls_draw.cpp
index 98bc9f661d..c4576acc86 100644
--- a/src/gl/scene/gl_walls_draw.cpp
+++ b/src/gl/scene/gl_walls_draw.cpp
@@ -166,7 +166,7 @@ void GLWall::SetupLights()
 void GLWall::RenderWall(int textured, unsigned int *store)
 {
 	static texcoord tcs[4]; // making this variable static saves us a relatively costly stack integrity check.
-	bool split = (gl_seamless && !(textured&RWF_NOSPLIT) && seg->sidedef != NULL && !(seg->sidedef->Flags & WALLF_POLYOBJ));
+	bool split = (gl_seamless && !(textured&RWF_NOSPLIT) && seg->sidedef != NULL && !(seg->sidedef->Flags & WALLF_POLYOBJ) && !(flags & GLWF_NOSPLIT));
 
 	tcs[0]=lolft;
 	tcs[1]=uplft;